Resource indexing for acknowledgement signals in response to receptions of multiple assignments

ABSTRACT

A method and apparatus for transmitting, by a user equipment, a hybrid automatic repeat request acknowledgement (HARQ-ACK) are provided. The method includes identifying a transmission power of the HARQ-ACK based on transmission power control information in first downlink control information for a primary cell; identifying, for a time division duplexing (TDD), a resource for transmission of the HARQ-ACK based on transmission power control information in second downlink control information with a downlink assignment index (DAI) value greater than 1; and transmitting the HARQ-ACK to a base station based on the resource on the primary cell.

PRIORITY

This application is a Continuation Application of U.S. application Ser.No. 14/021,403, filed in the U.S. Patent and Trademark Office on Sep. 9,2013, which is a Continuation Application of U.S. application Ser. No.12/986,675, filed in the U.S. Patent and Trademark Office on Jan. 7,2011, which issued as U.S. Pat. No. 8,543,124 on Sep. 24, 2013 andclaims priority under 35 U.S.C. §119(e) to a U.S. ProvisionalApplication No. 61/293,008, entitled “Indexing of Resources for theTransmission of Acknowledgement Signals in a Communication System withMultiple Component Carriers,” which was filed on Jan. 7, 2010, theentire contents of each of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to wireless communicationsystems and, more particularly, to the transmission of acknowledgmentsignals in the uplink of a communication system that are generated inresponse to the reception of multiple scheduling assignments.

2. Description of the Related Art

A communication system consists of a DownLink (DL), conveyingtransmissions of signals from a base station (also known as “Node B”) toUser Equipment (UEs), and of an UpLink (UL), conveying transmissions ofsignals from UEs to the Node B. A UE, also commonly referred to as aterminal or a mobile station, may be fixed or mobile and may be awireless device, a cellular phone, a personal computer device, or thelike. A Node B is generally a fixed station and may also be referred toas a Base Transceiver System (BTS), an access point, or the like.

The UL of the communication system supports transmissions of datasignals carrying the information content, control signals providinginformation associated with the transmission of data signals in the DLof the communication system, and Reference Signals (RS) which are alsoknown as pilot signals. The DL also supports transmissions of datasignals, control signals, and RS. UL data signals are conveyed throughthe Physical Uplink Shared CHannel (PUSCH). DL data channels areconveyed through the Physical Downlink Shared CHannel (PDSCH). In theabsence of PUSCH transmissions, a UE conveys Uplink Control Information(UCI) through the Physical Uplink Control CHannel (PUCCH), otherwise,UCI may be conveyed together with data in the PUSCH. DL control signalsmay be broadcast or UE related. UE-specific control channels can beused, among other purposes, to provide to UEs Scheduling Assignments(SAs) for PDSCH reception (DL SAs) or PUSCH transmission (UL SAs). TheSAs are transmitted from the Node B to respective UEs using DownlinkControl Information (DCI) formats through respective Physical DownlinkControl CHannels (PDCCHs).

UL control signals include acknowledgement signals associated with theapplication of a Hybrid Automatic Repeat reQuest (HARQ) process and aretypically in response to the correct, or incorrect, reception of thedata Transport Blocks (TBs) conveyed in the PDSCH. FIG. 1 illustrates aPUCCH structure for HARQ ACKnowledgement (HARQ-ACK) signal transmissionin a Transmission Time Interval (TTI), which in this example consists ofone sub-frame. The sub-frame 110 includes two slots. Each slot 120includes N_(symb) ^(UL) symbols for the transmission of HARQ-ACK signals130 or for Reference Signals (RS) 140 which enable coherent demodulationof the HARQ-ACK signals. Each symbol further includes a Cyclic Prefix(CP) to mitigate interference due to channel propagation effects. Thetransmission in the first slot may be at a different part of theoperating BandWidth (BW) than in the second slot in order to providefrequency diversity. The operating BW is assumed to consist of frequencyresource units which will be referred to as Resource Blocks (RBs). EachRB is assumed to consist of N_(sc) ^(RB) sub-carriers, or ResourceElements (REs), and a UE transmits HARQ-ACK signals and RS over one RB150.

FIG. 2 illustrates a structure for the HARQ-ACK signal transmissionusing a Constant Amplitude Zero Auto-Correlation (CAZAC) sequence in oneslot of the PUCCH. The transmission in the other slot is assumed toeffectively have the same structure. The HARQ-ACK bits b 210 modulate220 a CAZAC sequence 230, for example using Binary Phase Shift Keying(BPSK) or Quaternary Phase Shift Keying (QPSK) modulation, which is thentransmitted after performing an Inverse Fast Frequency Transform (IFFT)as it is next described. The RS 240 is transmitted through theunmodulated CAZAC sequence.

An example of CAZAC sequences is given by the following Equation (1):

$\begin{matrix}{{c_{k}(n)} = {\exp\left\lbrack {\frac{{j2\pi}\; k}{L}\left( {n + {n\frac{n + 1}{2}}} \right)} \right\rbrack}} & {{Eq}.\mspace{14mu}(1)}\end{matrix}$

where L is a length of the CAZAC sequence, n is an index of a sequenceelement, n={0,1,2, . . . , L−1}, and k is a sequence index. If L is aprime integer, there are L−1 distinct sequences which are defined as kranges in (1,2, . . . , L−1). Assuming that 1 RB includes N_(sc)^(RB)=12 REs, CAZAC sequences with even length can be directly generatedthrough computer search for sequences satisfying the CAZAC properties.

FIG. 3 illustrates a transmitter structure for a CAZAC sequence that canbe used without modulation as RS or with BPSK or QPSK modulation asHARQ-ACK signal. The frequency-domain version of a computer generatedCAZAC sequence is used in Step 310. The first RB and second RB areselected in Step 320, for transmission of the CAZAC sequence in thefirst slot and in the second slot, in Step 330, an IFFT is performed inStep 340, and a Cyclic Shift (CS), as it is subsequently described, isapplied to the output in Step 350. Finally, the CP is inserted in Step360 and filtering through time windowing is applied to the transmittedsignal 380. A UE is assumed to apply zero padding in REs that are notused for its signal transmission and in guard REs (not shown). Moreover,for brevity, additional transmitter circuitry such as digital-to-analogconverter, analog filters, amplifiers, and transmitter antennas as theyare known in the art, are not shown.

FIG. 4 illustrates a receiver structure for the HARQ-ACK signalreception. An antenna receives the RF analog signal and after furtherprocessing units (such as filters, amplifiers, frequencydown-converters, and analog-to-digital converters) the digital receivedsignal 410 is filtered in Step 420 and the CP is removed in Step 430.Subsequently, the CS is restored in Step 440, a Fast Fourier Transform(FFT) is applied in Step 450, the first RB and the second RB of thesignal transmission in Step 460 in the first slot and in the secondslot, are selected in Step 465, and the signal is correlated in Step 470with the replica of the CAZAC sequence in Step 480. The output 490 canthen be passed to a channel estimation unit, such as a time-frequencyinterpolator, in case of the RS, or to a detection unit for thetransmitted HARQ-ACK signal.

Different CSs of the same CAZAC sequence provide orthogonal CAZACsequences and can therefore be allocated to different UEs for HARQ-ACKsignal transmission in the same RB and achieve orthogonal UEmultiplexing. This principle is illustrated in FIG. 5. In order for themultiple CAZAC sequences 510, 530, 550, 570 generated correspondinglyfrom the multiple CSs 520, 540, 560, 580 of the same root CAZAC sequenceto be orthogonal, the CS value Δ 590 should exceed the channelpropagation delay spread D (including a time uncertainty error andfilter spillover effects). If T_(S) is the symbol duration, the numberof such CSs is equal to the mathematical floor of the ratio T_(S)/D thenumber of such CSs is └T_(S)/D┘ where the └ ┘ (floor) function rounds anumber to its lower integer.

In addition to orthogonal multiplexing of different HARQ-ACK signals inthe same RB using different CS of a CAZAC sequence, orthogonalmultiplexing can also be achieved in the time domain using OrthogonalCovering Codes (OCC). For example, in FIG. 2, the HARQ-ACK signal can bemodulated by a length-4 OCC, such as a Walsh-Hadamard (WH) OCC, whilethe

RS can be modulated by a length-3 OCC, such as a DFT OCC (not shown). Inthis manner, the multiplexing capacity is increased by a factor of 3(determined by the OCC with the smaller length). The sets of WH OCCs,{W₀, W₁, W₂, W₃}, and DFT OCCs, {D₀, D₁, D₂}, are:

${\begin{bmatrix}W_{0} \\W_{1} \\W_{2} \\W_{3}\end{bmatrix} = \begin{bmatrix}1 & 1 & 1 & 1 \\1 & {- 1} & 1 & {- 1} \\1 & 1 & {- 1} & {- 1} \\1 & {- 1} & {- 1} & 1\end{bmatrix}},\mspace{14mu}{\begin{bmatrix}D_{0} \\D_{1} \\D_{2}\end{bmatrix} = {\begin{bmatrix}1 & 1 & 1 \\1 & {\mathbb{e}}^{{- {j2\pi}}/3} & {\mathbb{e}}^{{- {j4\pi}}/3} \\1 & {\mathbb{e}}^{{- {j4\pi}}/3} & {\mathbb{e}}^{{- {j2\pi}}/3}\end{bmatrix}.}}$

Table 1 below presents an example for the mapping for the PUCCH resourcen_(PUCCH) used for a HARQ-ACK signal transmission to an OCC n_(OCC) anda CS α assuming a total of 12 CS per symbol for the CAZAC sequence.

TABLE 1 HARQ-ACK Resource Mapping to OCC and CS OC for HARQ-ACK and forRS CS W₀, D₀ W₁, D₁ W₃, D₂ 0 n_(PUCCH) = 0 n_(PUCCH) = 12 1 n_(PUCCH) =6 2 n_(PUCCH) = 1 n_(PUCCH) = 13 3 n_(PUCCH) = 7 4 n_(PUCCH) = 2n_(PUCCH) = 14 5 n_(PUCCH) = 8 6 n_(PUCCH) = 3 n_(PUCCH) = 15 7n_(PUCCH) = 9 8 n_(PUCCH) = 4 n_(PUCCH) = 16 9  n_(PUCCH) = 10 10n_(PUCCH) = 5 n_(PUCCH) = 17 11  n_(PUCCH) = 11

The SAs are transmitted in elementary units which are referred to asControl Channel Elements (CCEs). Each CCE consists of a number of REsand the UEs are informed of the total number of CCEs, N_(CCE), in a DLsub-frame through the transmission of a Physical Control FormatIndicator CHannel (PCFICH) by the Node B. For a Frequency DivisionDuplex (FDD) system, the UE determines n_(PUCCH) from the first CCE,n_(CCE), of the DL SA with the addition of an offset N_(PUCCH) the NodeB configures to the UE by higher layers (such as the Radio ResourceControl (RRC) layer) and n_(PUCCH)=n_(CCE)+N_(PUCCH). For a TimeDivision Duplex (TDD) system, the determination of n_(PUCCH) is moreinvolved but the same mapping principle using the CCEs of the DL SAapplies.

FIG. 6 further illustrates the transmission of an SA using CCEs. Afterchannel coding and rate matching of the SA information bits (not shown),the encoded SA bits are mapped to CCEs in the logical domain. The first4 CCEs, CCE1 601, CCE2 602, CCE3 603, and CCE4 604 are used for the SAtransmission to UE1. The next 2 CCEs, CCE5 611 and CCE6 612, are usedfor the SA transmission to UE2. The next 2 CCEs, CCE7 621 and CCE8 622,are used for the SA transmission to UE3. Finally, the last CCE, CCE9631, is used for the SA transmission to UE4. After further processingwhich can include bit-scrambling, modulation, interleaving, and mappingto REs 640, each SA is transmitted in the PDCCH region of the DLsub-frame 650. At the UE receiver, the reverse operations are performed(not shown for brevity) and if the SA is correctly decoded (asdetermined by the UE through a Cyclic Redundancy Check (CRC) which ismasked with the UE identity), the UE proceeds to receive the associatedPDSCH (DL SA) or to transmit the associated PUSCH (UL SA).

A one-to-one mapping exists between the resources for HARQ-ACK signaltransmission and the CCEs used for the DL SA transmission. For example,if a single resource is used for HARQ-ACK signal transmission, it maycorrespond to the CCE with the lowest index for the respective DL SA.Then, UE1, UE2, UE3, and UE4 use respectively PUCCH resource 1, 5, 7,and 9 for their HARQ-ACK signal transmission. Alternatively, if multipleCCEs are used for a DL SA transmission, HARQ-ACK information may notonly be conveyed by the modulated HARQ-ACK signal but it may also beconveyed by the selected resource (corresponding to one of the multipleCCEs used to convey the DL SA). If all resources within a PUCCH RB areused, the resources in the immediately next RB can be used.

In order to support data rates higher than the ones possible in legacyFDD communication systems operating with a single Component Carrier(CC), BWs larger than the ones of a CC for legacy communications may beused. These larger BWs can be achieved through the aggregation ofmultiple CCs. For example, a BW of 100 MHz results from the aggregationof five 20 MHz CCs. The Node B can configure communication with a UEover multiple CCs. The PDSCH reception by a UE in each DL CC isconfigured by a respective DL SA as described in FIG. 6. In TDD systems,higher data rates either in the DL or in the UL can be achieved byallocating a larger number of sub-frames to the specific link. Similarto the aggregation of multiple CCs, in case of multiple DL sub-frames,PDSCH reception in each DL sub-frame is configured by a respective DLSA.

The transmission of HARQ-ACK signals associated with DL SA receptions bya UE in multiple DL CCs can be in the PUCCH of a single UL CC which willbe referred to as “primary” UL CC for the UE (the primary UL CC isUE-specific). Separate resources in the primary UL CC can beRRC-configured to UEs for the transmission of HARQ-ACK signals inresponse to DL receptions in multiple DL CCs.

FIG. 7 illustrates the HARQ-ACK signal transmissions corresponding to DLSA receptions in 3 DL CCs, DL CC1 710, DL CC2 720, and DL CC3 730, thatoccur in the primary UL CC 740. The resources for the HARQ-ACK signaltransmissions corresponding to DL SA receptions in DL CC1, DL CC2, andDL CC3 are respectively in a first set 750, second set 760, and thirdset 770 of PUCCH resources.

A first approach for a UE to transmit HARQ-ACK signals in response to DLSA receptions in N>1 DL CCs is to simultaneously transmit in N>1HARQ-ACK channels in the respective resources of the primary UL CC. Asecond approach is to select the resource used for the HARQ-ACK signaltransmission depending on the value of the transmitted HARQ-ACK bits inaddition to transmitting a modulated HARQ-ACK signal, as in 3GPP EvolvedUniversal Terrestrial Radio Access (E-UTRA) Long Term Evolution (LTE)TDD. In both cases, separate resources for the HARQ-ACK signaltransmission are needed in response to DL SA reception for each DL CC. Athird approach is to jointly code all HARQ-ACK bits and transmit asingle HARQ-ACK signal in an exclusive RRC-configured resource for eachUE.

For the transmission of HARQ-ACK signals in the primary UL CC, if theprovisioned resources correspond to all CCEs used for SA transmissionsin each DL CC, the resulting overhead can be substantial as many DL CCsmay exist. A UE receiving SAs in a subset of the DL CCs may not know thenumber of CCEs used in other DL CCs and therefore cannot know the numberof respective HARQ-ACK resources in a sub-frame. As a consequence, themaximum number for the HARQ-ACK resources, corresponding to the maximumnumber of CCEs in each DL CC, needs to be assumed. If less than themaximum HARQ-ACK resources are used in a sub-frame, the remaining onescannot usually be assigned to other UL transmissions, such as PUSCHtransmissions, resulting to BW waste.

As the number of UEs with reception of DL SAs for multiple DL CCs persub-frame is typically not large, a pool of resources can be configuredby RRC for HARQ-ACK signal transmissions. The resource for HARQ-ACKsignal transmission in response to the DL SA reception for the DL CClinked to the primary UL CC can still be determined from the CCE withthe lowest index for the respective DL SA. The link between a DL CC andan UL CC is in the conventional sense of a single-cell communicationsystem. Assigning to each UE through RRC signaling unique resources forHARQ-ACK signal transmissions avoids resource collision but it resultsto resource waste if the UE does not have any DL SA reception in asub-frame. Assigning to a UE through RRC signaling shared resources withother UEs for HARQ-ACK signal transmissions reduces the probability ofresource waste at the expense of scheduler restrictions as UEs withshared resources for HARQ-ACK signal transmissions cannot receiverespective DL SAs in the same sub-frame.

The previous considerations apply regardless of the specific method usedfor the HARQ-ACK signal transmission in the PUCCH or the respectiveresource determination if one or more PUCCH resources need be reservedfor each UE while only a fraction of these resources is typically usedin each sub-frame.

Therefore, there is a need to reduce the resource overhead for HARQ-ACKsignal transmissions in a primary UL CC.

There is also a need to avoid collisions among resources for HARQ-ACKsignal transmissions from multiple UEs.

Finally, there is a need to determine rules for assigning resources forHARQ-ACK signal transmissions to a UE.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been designed to solve at leastthe above-mentioned limitations and problems in the prior art. Thepresent invention provides methods and apparatus for a UE to determinethe resource for an HARQ-ACK signal transmission in response to thereception by the UE of DL SAs transmitted by a Node B in multipleComponent Carriers (CCs) or multiple DL sub-frames.

According to an aspect of the present invention, a method fortransmitting, by a user equipment, a hybrid automatic repeat requestacknowledgement (HARQ-ACK) is provided. The method includes identifyinga transmission power of the HARQ-ACK based on transmission power controlinformation in first downlink control information for a primary cell;identifying, for a time division duplexing (TDD), a resource fortransmission of the HARQ-ACK based on transmission power controlinformation in second downlink control information with a downlinkassignment index (DAI) value greater than 1; and transmitting theHARQ-ACK to a base station based on the resource on the primary cell.

According to another aspect of the present invention, a method forreceiving, by a base station, a hybrid automatic repeat requestacknowledgement (HARQ-ACK) is provided. The method includes transmittingtransmission power control information in first downlink controlinformation for a primary cell for a transmission power of the HARQ-ACK;transmitting, for a time division duplexing (TDD), transmission powercontrol information in second downlink control information with adownlink assignment index (DAI) value greater than 1 for a resource fortransmission of the HARQ-ACK; and receiving the HARQ-ACK based on theresource on the primary cell.

According to another aspect of the present invention, am apparatus of bya user equipment for transmitting a hybrid automatic repeat requestacknowledgement (HARQ-ACK) is provided. The apparatus includes acontroller configured to identify a transmission power of the HARQ-ACKbased on transmission power control information in first downlinkcontrol information for a primary cell, and identify, for a timedivision duplexing (TDD), a resource for transmission of the HARQ-ACKbased on transmission power control information in second downlinkcontrol information with a downlink assignment index (DAI) value greaterthan 1; and a transmitter configured to transmit the HARQ-ACK to a basestation based on the resource on the primary cell.

According to another aspect of the present invention, an apparatus of abase station for receiving a hybrid automatic repeat requestacknowledgement (HARQ-ACK), the apparatus includes a transmitterconfigured to transmit transmission power control information in firstdownlink control information for a primary cell for a transmission powerof the HARQ-ACK, and transmit, for a time division duplexing (TDD),transmission power control information in second downlink controlinformation with a downlink assignment index (DAI) value greater than 1for a resource for transmission of the HARQ-ACK; and a receiverconfigured to receive the HARQ-ACK based on the resource on the primarycell.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of the presentinvention will be more apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating a PUCCH sub-frame structure for thetransmission of a HARQ-ACK signal;

FIG. 2 is a diagram illustrating a structure for a HARQ-ACK signaltransmission using a CAZAC sequence in one slot of a PUCCH sub-frame;

FIG. 3 is a block diagram illustrating a transmitter structure for aCAZAC sequence;

FIG. 4 is a block diagram illustrating a receiver structure for a CAZACsequence;

FIG. 5 is a diagram illustrating a multiplexing of CAZAC sequencesthrough the application of different cyclic shifts;

FIG. 6 is a block diagram illustrating the transmission of SAs usingPDCCH CCEs;

FIG. 7 is a diagram illustrating the availability of different resourcesfor HARQ-ACK signal transmission in an UL CC in response to thereception of multiple SAs for respective multiple DL CCs;

FIG. 8 is a diagram illustrating an example for the generation ofHARQ-ACK signal transmission resource using the CCEs conveying themultiple SAs for the respective multiple DL CCs assuming that the UEreceives all SAs in the DL CC linked to the primary UL CC, according toan embodiment of the present invention;

FIG. 9 is a diagram illustrating an example for the generation ofHARQ-ACK signal transmission resource using RRC configured resourcesassuming that the UE receives multiple SAs for respective multiple DLCCs where some SAs are received in DL CCs not linked to the primary ULCC, according to an embodiment of the present invention;

FIG. 10 illustrates the principle of using the bits of the TPC IE in DLSAs to index the resource for the HARQ-ACK signal a UE transmits inresponse to the reception of multiple DL SAs, according to an embodimentof the present invention;

FIG. 11 illustrates a step-wise mapping between the offset applied toRRC-configured HARQ-ACK resources and the values for the TPC IE,according to an embodiment of the present invention;

FIG. 12 illustrates a serial mapping between the offset applied to theRRC-configured HARQ-ACK resources and the values for the TPC IE,according to an embodiment of the present invention;

FIG. 13 illustrates a HARQ-ACK resource mapping for DL SAs in DL CCs,other than the primary DL CC, as a function of the resource for theprimary DL CC, the TPC IE, and the DAI IE in the respective DL SAs,according to an embodiment of the present invention;

FIG. 14 illustrates a block diagram of the HARQ-ACK signal transmitterincluding a controller for selecting the resource according to the TPCIE value, according to an embodiment of the present invention; and

FIG. 15 illustrates a block diagram of the HARQ-ACK signal receiverincluding a controller for selecting the resource according to the TPCIE value, according to an embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein. Rather, these embodiments areprovided so that the disclosure is thorough and complete and fullyconveys the scope of the invention to those skilled in the art.

Additionally, although the present invention is described in relation toan Orthogonal Frequency Division Multiple Access (OFDMA) communicationsystem, it also applies to all Frequency Division Multiplexing (FDM)systems in general and to Single-Carrier Frequency Division MultipleAccess (SC-FDMA), OFDM, FDMA, Discrete Fourier Transform (DFT)-spreadOFDM, DFT-spread OFDMA, SC-OFDMA, and SC-OFDM in particular.

Methods and apparatus are described for a UE to determine the resourcefor a HARQ-ACK signal transmission, in response to multiple DL SAreceptions in multiple DL CCs or in multiple DL sub-frames.

One aspect of the present invention provides the relative indexing ofavailable resources for HARQ-ACK signal transmissions in the primary ULCC. These resources may be RRC-configured or dynamically determinedthrough the respective DL SA. RRC-configured resources can be consideredbut the same principles directly apply for dynamically determined ones(repeating such description is omitted for brevity).

In the first case, all UEs having HARQ-ACK signal transmission in thesame primary UL CC are also assumed to receive SAs in the DL CC linkedto the primary UL CC or be able to reliably receive the correspondingPCFICH. The DL CC linked to the primary UL CC will be referred to asprimary DL CC. The resource for HARQ-ACK signal transmission in responseto a DL SA for the primary DL CC is assumed to be determined from theCCE with the lowest index for the respective DL SA. The resource forHARQ-ACK signal transmission in response to a DL SA for a DL CC otherthan the primary DL CC is configured through RRC signaling for each UEand is determined relative to the total number of resources required forHARQ-ACK signal transmissions in response to DL SAs in the primary DL CCwhich are in turn determined by the PDCCH size in the primary DL CC.

FIG. 8 illustrates the first case described above. In the primary DL CC,the PDCCH occupies P CCEs in sub-frame p 810 and Q CCEs in sub-frame q820. As each UE having the same primary UL CC receives a SA in theprimary DL CC, or reliably receives the PCFICH in the primary DL CC, itknows the available resources for the transmission of HARQ-ACK signalsin the primary UL CC in response to DL SAs in the primary DL CC (DLCC1). These resources are determined by the total number of CCEs in theprimary DL CC which equal P in sub-frame p 830 and Q in sub-frame q 840.Therefore, a UE knows that its RRC-configured resources for HARQ-ACKsignal transmissions are indexed after the P+N_(PUCCH) resource insub-frame p (the first RRC-configured resource is indexed asP+1+N_(PUCCH) and counting starts from 1) and are indexed after theQ+N_(PUCCH) resource in sub-frame q (the first RRC-configured resourceis indexed as Q+1+N_(PUCCH)). Assuming that the number of RRC-configuredresources for HARQ-ACK signal transmission corresponding to DL SAreceptions in sub-frames p and q are respectively N_(CA)(p) andN_(CA)(q), the total number of resources for HARQ-ACK signaltransmissions in sub-frame p is P+N_(PUCCH)+N_(CA)(p) 850 and the totalnumber of resources for HARQ-ACK signal transmissions in sub-frame q isQ+N_(PUCCH)+N_(CA)(q) 860. The resource indexing before the beginning ofeach region is shown for the upper part of the BW is sub-frame p, 870,872, 874, and can be extended in the same manner for the lower part ofthe BW and for sub-frame q (omitted for brevity). A single value ofN_(CA) may apply to all sub-frames, that is N_(CA)(p)=N_(CA)(q), ∀p, q,until updated through broadcast signaling. Moreover, as the Node B knowsof the resources used by each UE, the UEs may not need to be informed ofthe N_(CA) value if they determine the resources for HARQ-ACK signaltransmissions in response to DL SAs for DL CCs other than the primary DLCC relative to the total number of resources for HARQ-ACK signaltransmissions in response to DL SAs in the primary DL CC.

In the second case, some of the UEs having HARQ-ACK signal transmissionsin the same primary UL CC do not receive a SA in the primary DL CC andcannot be assumed to reliably receive the PCFICH in the primary DL CC.Then, the resources for HARQ-ACK signal transmissions in response to DLSAs in DL CCs other than the primary DL CC are still RRC-configured foreach UE but they are determined relative to the maximum number ofresources required for HARQ-ACK signal transmissions in response to DLSAs in the primary DL CC. That is, the maximum PDCCH size in a givensub-frame is always assumed in the primary DL CC for the purposes ofindexing the resources for HARQ-ACK signal transmissions in response toDL SAs for DL CCs other than the primary DL CC. The resources forHARQ-ACK signal transmissions in response to DL SAs transmitted in theprimary DL CC are still determined from the CCE with the lowest indexfor the respective DL SA.

FIG. 9 illustrates the second case described above. In the primary DLCC, the PDCCH occupies P CCEs in sub-frame p 910 while the PDCCHoccupies Q CCEs in sub-frame q 920. As some UEs having the same primaryUL CC do not receive a SA and do not reliably receive the PCFICH in theprimary DL CC, each such UE cannot know the resources required for thetransmission of HARQ-ACK signals in the primary UL CC in response to DLSAs in the primary DL CC (DL CC1). These resources are determined by thetotal number of CCEs in the primary DL CC for the transmission of SAswhich equal P in sub-frame p 930 and Q in sub-frame q 940. Therefore, ifN_(max)(j) are the maximum number of CCEs for SA transmissions insub-frame j, a UE knows that its RRC configured resources for HARQ-ACKsignal transmissions are indexed after the N_(max)(j)+N_(PUCCH)resources (the first RRC-configured resource is indexed asN_(max)(j)+1+N_(PUCCH), counting starts from 1). Assuming that the lastRRC-configured resource for HARQ-ACK signal transmission in sub-frame pis N_(CA)(p) and the last RRC-configured resource for HARQ-ACK signaltransmission in sub-frame q is N_(CA)(q), the total number of resourcesfor HARQ-ACK signal transmissions in sub-frame p isN_(max)(p)+N_(PUCCH)+N_(CA)(p) 950 and the total number of resources forHARQ-ACK signal transmissions in sub-frame q isN_(max)(q)+N_(PUCCH)+N_(CA)(q) 960. The resource indexing before thebeginning of each region is shown for the upper part of the BW issub-frame p, 970, 972, 974, and can be extended in the same manner forthe lower part of the BW and for sub-frame q (omitted for brevity).

Another aspect of the present invention provides the actual indexing ofRRC-configured, or dynamically determined through the respective DL SA,resources for HARQ-ACK signal transmissions in the primary UL CC.

Once the relative indexing of the RRC-configured (or dynamicallydetermined) resources for HARQ-ACK signal transmissions in the primaryUL CC is determined, additional indexing of the RRC-configured (ordynamically determined) resources is needed in order to avoid a largeoverhead. This is because even if the number of UEs having DL SAs inmultiple DL CCs per sub-frame is small, many UEs potentially having DLSAs in multiple DL CCs may exist and, as they are configured resourcesfor HARQ-ACK signal transmissions through RRC signaling, these resourcesneed to remain assigned to UEs even if they do not have any DL SAs in asub-frame since fast reassignment of RRC-configured resources is eithernot possible or is inefficient in terms of the required signaling.

Assuming a total of M UEs potentially having a DL SA in each of K DL CCsand that the resource for each HARQ-ACK signal transmission in responseto a DL SA in the primary DL CC is determined from the CCE with thelowest index for the respective DL SA, the number of RRC-configuredresources is M·(K−1). For M=100 and an average value of K=3, a total of200 resources need to be RRC-configured to each UE in order to uniquelyassign each resource and avoid potential collisions or schedulerrestrictions. Further assuming a multiplexing capacity of 18 HARQ-ACKsignals per RB, as described in Table 1, a total of about 11 RBs isrequired in the primary UL CC to support HARQ-ACK transmissions inRRC-configured resources. This overhead is substantial although it is aconservative estimate as multiplexing 18 HARQ-ACK signals in a single RBresults significant interference (the interference increases by10log₁₀(18)=12.55 deciBels (dBs) relative to a single HARQ-ACK signaltransmission per RB). Additionally, more than M=100 UEs may beconfigured DL SA reception in multiple DL CCs (although only a smallfraction of them may actually have DL SA reception per sub-frame). Toreduce the overhead associated with RRC-configured resources forHARQ-ACK signal transmissions, the invention provides that theseresources may be shared among UEs and additional indexing can apply toavoid potential collisions.

A DL SA conveys multiple Information Elements (IEs) enabling differentaspects for PDSCH reception. Among the IEs in the DL SA is the IEproviding Transmission Power Control (TPC) commands in order for the UEto adjust the power of the subsequent HARQ-ACK signal transmission.Since the HARQ-ACK signal transmission is assumed to be in the primaryUL CC, and not in multiple UL CCs, only a single TPC command is needed.The invention provides that this TPC IE is provided by the DL SAtransmitted in the primary DL CC a UE is configured and, with multiplesuch DL SAs, the TPC command is provided by the DL SA scheduling PDSCHreception in the primary DL CC. The invention also provides that all DLSAs include the TPC IE, regardless if the TPC IE from only one DL SA isused for its intended purpose. The remaining TPC IEs (which may be setto have the same value) can be used to index the RRC-configuredresources for the HARQ-ACK signal transmissions corresponding to therespective DL SAs. Therefore, for a given UE, denoting by n_(PUCCH)(0)the resource available for HARQ-ACK signal transmission corresponding tothe DL SA for the primary DL CC, and by n_(PUCCH)(j), j>0 the resourceavailable for HARQ-ACK signal transmission corresponding to the DL SA ina DL CC other than the primary DL CC, it is:n _(PUCCH)(j)=ƒ(n _(PUCCH)(0), TPC(j)), j>0The present invention also provides that the above embodiment utilizingthe TPC IE to dynamically index RRC-configured resources for HARQ-ACKsignal transmissions can be generalized to include the introduction of anew IE in the DL SAs that is used for such indexing. Denoting the IEused for HARQ-ACK Resource Indexing as HRI IE, the resource used forHARQ-ACK signal transmission can be determined asn _(PUCCH)(j)=ƒ(n _(PUCCH)(0), HRI(j)), j>0

where j denotes the DL CC index. The HRI IE may also be used to indexthe resources for HARQ-ACK signal transmissions in response to DL SAs inthe primary DL CC (the link to the lowest CCE index may not apply).

FIG. 10 illustrates indexing the resource for the HARQ-ACK signaltransmission in response to the reception of multiple DL SAs using theTPC IE bits in the DL SAs. The TPC IE in DL SA1 in the primary DL CC1010 is used by the UE to determine the power for the HARQ-ACK signaltransmission 1020 in response to the respective DL SA reception. The TPCIE in DL SA 2 1030 through DL SA K 1050 is used as an index for the RRCconfigured resource for the HARQ-ACK signal transmission 1040 through1060, respectively.

FIG. 11 and FIG. 12 illustrate two specific examples for the generalprinciple in FIG. 10. A UE is assumed to have configured K=5 DL CCs. TheTPC IE consists of 2 bits having the values “00”, “01”, “10”, and “11”with each value corresponding to a different offset of theRRC-configured resource for HARQ-ACK signal transmission when the TPC IEis used to index the resource of the HARQ-ACK signal transmission.

FIG. 11 illustrates a step-wise mapping between the offsets applied tothe RRC-configured HARQ-ACK resource and the values for the TPC IE bits.The possible mappings are illustrated by reference numeral 1110 where“00” indicates offset 0, “01” indicates offset 4, “10” indicates offset8, and “11” indicates offset 16. UE1 1120, UE 2 1130, and UE3 1140 haveoverlapping RRC-configured HARQ-ACK resources. UE4 1150, UE 5 1160, andUE 6 1170 also have overlapping RRC-configured HARQ-ACK resources.Despite the compactness of RRC-configured HARQ-ACK resources (only 8resources are configured when 18 are needed), the offset applied throughthe indexing using the TPC IE bits in the respective DL SAs, 1122, 1132,1142, 1152, 1162, and 1172 removes the overlapping from the resultingHARQ-ACK resources 1124, 1134, 1144, 1154, 1164, and 1174, respectively.The mapping for the resulting resources for HARQ-ACK signal transmissionis relatively compact as 24 resources are used when the minimum is 18(some redundancy is desirable to reduce the interference HARQ-ACKsignals experience). It is also observed that the TPC IE bits in each DLSA, other than the DL SA in the primary DL CC, for a given UE have thesame value.

FIG. 12 illustrates a serial mapping between the offsets applied to theRRC-configured HARQ-ACK resource and the values for the TPC IE bits. Thepossible mappings are illustrated by reference numeral 1210 where “00”indicates offset 0, “01” indicates offset 1, “10” indicates offset 2,and “11” indicates offset 3. UE1 1220, UE2 1230, and UE3 1240 haveoverlapping RRC-configured HARQ-ACK resources. UE4 1250, UE5 1260, andUE6 1270 also have overlapping RRC-configured HARQ-ACK resources. Theoffset applied through the indexing using the TPC IE bits in therespective DL SAs, 1222, 1232, 1242, 1252, 1262, and 1272 removes theoverlapping from the resulting HARQ-ACK resources 1224, 1234, 1244,1254, 1264, and 1274, respectively. The mapping for the resultingresources for HARQ-ACK signal transmission is again compact as 21resources are used when the minimum is 18. Basically, the RRC-configuredresources need to consider the maximum number of UEs having reception ofDL SAs in multiple DL CCs per sub-frame and the number of such DL CCs.The 2 bits in the TPC IE can then be used to avoid the collision ofresources for the HARQ-ACK signal transmission from up to 4 UEs thathappen to have the same RRC-configured HARQ-ACK resource for the DL SAin a DL CC.

Another aspect of the present invention provides resource determinationfor the HARQ-ACK signal transmission when a DL SA also includes acounter IE, which will be referred to as Downlink Assignment Indicator(DAI) IE, which indicates the number of the DL SA. For example, if a UEis configured 4 DL CCs, the DAI IE may have the values of 1, 2, 3, and 4in the DL SAs scheduling PDSCH reception in the primary DL CC, and inthe second, third, and fourth DL CCs, respectively. The same applies fora TDD system and single CC operation, with DL sub-frames replacing DLCCs, and the DAI IE may have the values of 1, 2, 3, and 4 in the DL SAsscheduling PDSCH reception in the first, second, third, and fourth DLsub-frames, respectively. The TPC IE provided by the DL SA schedulingPDSCH reception in the primary DL CC, or in the first DL sub-frame forTDD systems, is used to determine the power of the HARQ-ACK signaltransmission.

Each resource for HARQ-ACK signal transmission in response to PDSCHreception in each of the remaining DL CCs or DL sub-frames (other thanthe primary DL CC or the first DL sub-frame) is determined as a functionof the resource corresponding to the primary DL CC or the first DLsub-frame, the TPC IE and the DAI IE in the DL SAs for the respective DLCCs or DL sub-frames. For a given UE, denoting by n_(PUCCH)(0) theresource used for the HARQ-ACK signal transmission in the primary DL CCor first DL sub-frame, and by n_(PUCCH)(j), j>0 the resource used in aDL CC or DL sub-frame other than the primary DL CC or first DLsub-frame, respectively, it is:n _(PUCCH)(j)=ƒ(n _(PUCCH)(0), HRI(j), DAI(j)), j>0.

Moreover, as previously mentioned, a HRI IE may be introduced in the DLSAs for indexing the resource used for the respective HARQ-ACK signaltransmission. Then, the resource can be determined as:n _(PUCCH)(j)=ƒ(n _(PUCCH)(0), HRI(j), HRI(j)), j>0.

FIG. 13 illustrates resource mapping for HARQ-ACK signal transmission inresponse to the reception of DL SAs in DL CCs, other than the primary DLCC, as a function of the resource corresponding to the primary DL CC,the TPC IE, and the DAI IE in the respective DL SA. The TPC IE bits ineach DL SA, other than the DL SA for the primary DL CC, are used toindicate the HARQ-ACK signal transmission resource. The possiblemappings are illustrated by reference numeral 1310 where “00” indicatesoffset 1, “01” indicates offset 2, “10” indicates offset 3, and “11”indicates offset 4. The offset values may also depend on whether the UEis configured transmitter diversity for the HARQ-ACK signal transmissionin which case different offset values may be used, such as 2, 4, 6, and8, respectively (assuming 2 transmitter antennas). UE1, UE2, UE3, UE4,UE5, and UE6 successfully receive DL SAs in 4, 2, 3, 3, 4, and 2 DL CCs(other than the primary DL CC), respectively, with each DL SA conveyinga TPC IE value 1322, 1332, 1342, 1352, 1362, and 1372, respectively. Inthe mapping of FIG. 13, the resource for the HARQ-ACK signaltransmission is obtained by scaling the offset value specified by theTPC IE by the value of the DAI IE and adding the result to the resourcefor the HARQ-ACK signal transmission in response to the DL SA receptionin the primary DL CC, 1324, 1334, 1344, 1354, 1364, and 1374,respectively. The DAI IE values are in ascending order for each DL SAreception (starting from 0 for the PDSCH reception in the primary DLCC). Therefore, for a given UE in FIG. 13, the resource n_(PUCCH)(j),j>0 for HARQ-ACK signal transmission in response to PDSCH reception inDL CC j is n_(PUCCH)(j)=n_(PUCCH)(0)+TPC−DAI, j>0.

FIG. 14 illustrates a block diagram of the UE transmitter for theHARQ-ACK signal transmission. The main components are as described inFIG. 3 with the exception that the RRC-configured resource used for theHARQ-ACK signal transmission depends on the offset specified by thecontroller for the mapping of the TPC IE (or of the HRI IE) value 1490which the UE obtains from the respective DL SA. The frequency-domainversion of a computer generated CAZAC sequence 1410 is used. The CAZACsequence is mapped to a sub-carrier 1430, IFFT is performed 1440 and acyclic shift 1450 is performed. The resource includes the RB 1420 andthe CS 1450 (and also the OCC—not shown for simplicity). FIG. 14 can bemodified in a trivial manner for the controller to include the DAI IE,in addition to the TPC IE. Finally, the CP 1460 and filtering 1470 areapplied to the transmitted signal 1480.

FIG. 15 illustrates a block diagram of the Node B receiver for theHARQ-ACK signal reception. The main components are as described in FIG.4 with the exception that the RRC—configured resource used for theHARQ-ACK signal reception depends on the offset specified by thecontroller for the mapping of the TPC IE (or of the HRI IE) value 1510which the Node B included in the respective DL SA. The resource includesthe RB 1565 and the CS 1530 (and also the OCC—not shown for simplicity).The digital received signal 1510 is filtered 1515 and the CP is removed1525. Subsequently, the CS is restored 1530, a Fast Fourier Transform(FFT) 1535 is applied and the output of the FFT 1535 is de-mapped to asub-carrier 1540. And the signal is correlated by the multiplier in Step1545 with the replica of the CAZAC sequence in Step 1550. The output1560 can then be passed to a channel estimation unit, such as atime-frequency interpolator for the RS, or to a detection unit for thetransmitted HARQ-ACK signal.

FIG. 15 can be modified in a trivial manner for the controller toinclude the DAI IE, in addition to the TPC IE.

While the present invention has been shown and described with referenceto certain embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims.

What is claimed is:
 1. A method for transmitting, by a user equipment, ahybrid automatic repeat request acknowledgement (HARQ-ACK), the methodcomprising: identifying a transmission power of the HARQ-ACK based ontransmission power control information in first downlink controlinformation for a primary cell; identifying, for a time divisionduplexing (TDD), a resource for transmission of the HARQ-ACK based ontransmission power control information in second downlink controlinformation with a downlink assignment index (DAI) value greater than 1;and transmitting the HARQ-ACK to a base station based on the resource onthe primary cell.
 2. The method of claim 1, wherein the transmissionpower control information in the second downlink control informationwith a DAI value greater than 1 indicates the resource among a set ofresources configured by the base station.
 3. The method of claim 2,wherein the user equipment assumes that the resource is the same for allsecond downlink control information used to identify the resource. 4.The method of claim 1, wherein bits of the HARQ-ACK for all subframesare jointly coded.
 5. The method of claim 1, wherein the resource isused for resource selection.
 6. A method for receiving, by a basestation, a hybrid automatic repeat request acknowledgement (HARQ-ACK),the method comprising: transmitting transmission power controlinformation in first downlink control information for a primary cell fora transmission power of the HARQ-ACK; transmitting, for a time divisionduplexing (TDD), transmission power control information in seconddownlink control information with a downlink assignment index (DAI)value greater than 1 for a resource for transmission of the HARQ-ACK;and receiving the HARQ-ACK based on the resource on the primary cell. 7.The method of claim 6, wherein the transmission power controlinformation in the second downlink control information with a DAI valuegreater than 1, indicates the resource among a set of resourcesconfigured by the base station.
 8. The method of claim 6, wherein theresource is the same for all second downlink control information used toidentify the resource by a user equipment.
 9. The method of claim 6,wherein bits of the HARQ-ACK for all subframes are jointly coded. 10.The method of claim 6, wherein the resource is used for resourceselection.
 11. An apparatus of by a user equipment for transmitting ahybrid automatic repeat request acknowledgement (HARQ-ACK), theapparatus comprising: a controller configured to identify a transmissionpower of the HARQ-ACK based on transmission power control information infirst downlink control information for a primary cell, and identify, fora time division duplexing (TDD), a resource for transmission of theHARQ-ACK based on transmission power control information in seconddownlink control information with a downlink assignment index (DAI)value greater than 1; and a transmitter configured to transmit theHARQ-ACK to a base station based on the resource on the primary cell.12. The apparatus of claim 11, wherein the transmission power controlinformation in the second downlink control information with a DAI valuegreater than 1, indicates the resource among a set of resourcesconfigured by the base station.
 13. The apparatus of claim 12, whereinthe controller assumes that the resource is the same for all seconddownlink control information used to identify the resource.
 14. Theapparatus of claim 11, wherein bits of the HARQ-ACK for all subframesare jointly coded.
 15. The apparatus of claim 11, wherein the resourceis used for resource selection.
 16. An apparatus of a base station forreceiving a hybrid automatic repeat request acknowledgement (HARQ-ACK),the apparatus comprising: a transmitter configured to transmittransmission power control information in first downlink controlinformation for a primary cell for a transmission power of the HARQ-ACK,and transmit, for a time division duplexing (TDD), transmission powercontrol information in second downlink control information with adownlink assignment index (DAI) value greater than 1 for a resource fortransmission of the HARQ-ACK; and a receiver configured to receive theHARQ-ACK based on the resource on the primary cell.
 17. The apparatus ofclaim 16, wherein the transmission power control information in thesecond downlink control information with a DAI value greater than 1,indicates the resource among a set of resources configured by the basestation.
 18. The apparatus of claim 16, wherein the resource is the samefor all second downlink control information used to identify theresource by a user equipment.
 19. The apparatus of claim 16, whereinbits of the HARQ-ACK for all subframes are jointly coded.
 20. Theapparatus of claim 16, wherein the resource is used for resourceselection.